The present invention relates to a liquid sensor mounted on a side wall or the like of a liquid tank for detecting the existence of liquid in the tank.
An apparatus for detecting liquids, such as a liquid level indicator, in which a plurality of electrodes provided at intervals are electrically connected through a liquid when contacted with said liquid, has been known.
However, an apparatus having such a construction has such a disadvantage that it cannot be used for the detection of electrically nonconductive liquids.
Further, it has a problem of corrosion since the electrodes are exposed to liquids, that is to say, they are brought into direct contact with liquids and it is difficult to miniaturize such an apparatus.
In addition, although a detecting apparatus of the float-switch type has also been known in addition to the above described one of the electrode type, the float-switch type detecting apparatus is also difficult to miniaturize, and is subject to frequent malfunction since it contains movable parts therein.
Thus, it is a first object of the present to provide a liquid sensor which can detect even electrically nonconductive liquids independently of the kind of liquids.
It is a second object of the present invention to provide a remarkably miniaturized liquid sensor which will not to malfunction.
It is a third object of the present invention to provide a liquid sensor having electrodes which will not corrode owing to the contact with liquids thereof and can be easily electrically mounted on a liquid tank.
It is a fourth object of the present invention to provide a liquid sensor which can be easily incorporated in an electric circuit since it can be directly operated with electric signals.